Yamaha YZ250(W)/W1, Owner'S Service Manual

Page: 216 / 596

3-40
IGNITION TIMING CHECK
INSP
ADJ
EC372012
IGNITION TIMING CHECK
1. Remove:
9 Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
9 Spark plug
9 Crankcase cover (left)
2. Attach:
9 Dial gauge
1
9 Spark plug hole dial stand
2
3. Rotate the magneto rotor 1 until the piston
reaches top dead center (TDC). When this
happens, the needle on the dial gauge will
stop and reverse directions even though the
rotor is being turned in the same direction.
4. Set the dial gauge to zero at TDC.
5. From TDC, rotate the rotor clockwise until
the dial gauge indicates that the piston is at
a specified distance from TDC.
6. Check:
9 Ignition timing
Punch mark
a
on rotor should be aligned
with punch mark
b
on stator.
Not aligned
→
Adjust.
Dial gauge:
YU-3097/90890-01252
Spark plug hole dial stand:
YU-1256
Ignition timing (B.T.D.C.):
0.18 mm (0.007 in)
1P8-9-32-3b 5/1/06 9:41 AM Page 48